Brendan, I think 10 is a double definition. First defn. is "number 10 in table" and the second is the entirety of the solution of 11 across (imagine inverted commas surrounding the first two words of 11a).
Hi Brendan
The first part of 12 is the definition.
The second part takes you to the solution to 11, which you have to take as a whole as constituting the cryptic element of 12.
Pace Geeker, I don’t think 12 is strictly speaking a double definition (there is one elsewhere). It’s a definition plus a cryptic element (as to which we agree on the parsing).
I know that you're going to hate me for saying this, but I can't be alone in wishing that the Saturday Prize Crossword was a bit more challenging than a midweek write-in.
This was a duty rather than a pleasure.